It was not with very light hearts that they started back, and for a time they went cautiously. Then, as they seemed to get on familiar ground, they increased their pace and covered several miles. "Say," remarked. Jack, as he sat down on a big stone. "I don't know how the rest of you feel, but I'm tired. We've come quite a distance since we picked up that tool." "Yes, farther than it took us to find it after we left the projectile," added Mark. "I wonder if we're going right?" The two boys looked at Andy. He scratched his head in perplexity. "I can't be sure, but it seems to me that we came past here," he said. "I seem to remember that big rock." "There are lots like it," observed Jack. "Suppose we try over to the left," spoke Mark, after they had rested for ten minutes. They swerved in that direction, and, after keeping on that trail for some time, and becoming more and more convinced that it was the wrong one, they turned to the right. That did not bring them to familiar ground, and there was no sight of the projectile. "Let's go straight ahead," suggested Andy, after a puzzled pause. "I think that will be best." "Well, which way is straight ahead?" asked Mark. "That's so, it is hard to tell," admitted the hunter. "I wish I hadn't lost that compass." They wandered about for an hour longer. They could seem to make no progress, though they covered much ground. Suddenly Jack called out: "Say, we've been going around in a circle!" "In a circle?" asked Mark. "Yes," went on his chum. "Here's the very rock I sat down on a while ago. I remember it, for I scratched my initials on it." Jack pointed out the letters. There was no disputing it. They had made a complete circle. For a moment they maintained silence in the face of this alarming fact. Then Mark exclaimed: "I guess we're lost!" "Lost on the moon!" added Jack, in an awestruck voice, and he gazed on the chill and desolate scene all about them; the great pinnacles of rocks, in fantastic form; the immense black caverns of craters on either hand; the sickly green vegetation. "Lost on the moon!" whispered Mark, and there was not even an echo of his voice to keep them company. Only a chill, desolate silence! CHAPTER XXIV DESOLATE WANDERINGS For a moment the three stood helplessly there and stared at each other. They could scarcely comprehend their situation at first. Then, with a glance at the cold and quiet scene all about them, a look up at the sun, which was the only cheerful object in the whole landscape, Jack observed: "Oh, I say, come on now, don't let's give up this way! We have only taken a wrong turn, and I'll wager that the projectile will be just around the corner. Come on," and he started off. "Yes," said Mark, "that's the trouble. There are so many corners, and we have taken so many wrong turns, that we're all confused. I think the best thing to do will be to stay here a while and pull ourselves together."